This invention relates to managing call flows between environments having different signaling protocols, and particularly between an asynchronous transfer mode (ATM) environment and a local area network (LAN) environment. The invention is based on using the ATM broadband integrated services digital networks (BISDN) signaling protocol for establishing multimedia calls for the multimedia terminals in the local area network. The invention is particularly directed to multi-media communication exchange (MMCX) call flows using BISDN signaling in LANs.
In a LAN environment, applications on two different hosts communicate with each other by transmitting messages containing their internet addresses and port number addresses. When one user wishes to send a message to another user, it requires sending the message on the internet address and the port number address of the second user. Similarly, if the second user wants to send messages to the first user, the second user needs to send the internet address and port number address of the first user. One way of establishing the call is to have the first user send its internet and port number addresses to the second user and similarly have the second user send its internet and port number addresses to the first user.
In ATM signaling protocols, and particularly to BISDN signaling protocols, there are two distinct information elements (IEs) to be considered. The first IE in the virtual channel identifier (VCI) which is used to assign the virtual channels. The second IEs are the directory number (DN) IEs for the calling and called parties, which differ from the VCIs.
Call flows for multi-media communication exchanges (MMCX) require an initialization process before any users place a call. Such initialization may begin when a user logs into a terminal. The initialization process at this stage means establishing two signaling channels between a client and a server. One of the signaling channels establishes the communication between a call control agent at the terminal endpoint and a call control at the server. The other signaling channel establishes communication between a bearer control at the client and server. The client should have the internet address of the server. If for any reason, the client does not have the server""s internet address, it will broadcast a reverse address resolution protocol (RARP) message to the network in order to request the server""s internet address. The server responds by transmitting the server""s internet address. The client should also have access to the initial port numbers of itself and the server.
An embodiment of the invention involves identifying in the one signaling protocol that the call is going to the environment having the other signaling protocol, replacing a first signaling element of the one signaling protocol with the corresponding second signaling element of the second protocol, and completing the call on the basis of the first signaling protocol with the corresponding second signaling element of the second protocol.
Another embodiment involves signaling with an ATM or BISDN protocol to a LAN protocol block by sending port numbers in the VCI (virtual channel identifier) field of ATM signals and the internet addresses in the directory number for the calling and called parties.
The various features of novelty that characterize the invention are pointed out in the claims. Objects and advantages of the invention will become evident from the following detail description in read in light of the accompanying drawings.